This invention relates to a Thermal adhesive type coating composition having simultaneously the function of a protective material when the coating is applied to the surface of a variety of base materials, such as metals, plastics or inorganic materials, and the function of an adhesive having a strong adhesive strength when the composition is applied to the surfaces of two of the base materials and the coated surfaces of these base materials are applied to each other under heating and pressure application at a desired later time after the formation of the coatings.
For protecting and improving the aesthetic aspect of a variety of base materials, a variety of paints have been employed, while a variety of adhesives have also been employed extensively for bonding two base materials to each other.
However, there has scarcely been known a composition having not only the function of protecting the base material but also the function of bonding two base materials to each other. The practical merit would be outstanding if these two functions could be realized in the same composition. For example, in the case of a precoated metal (PCM), the paint is previously applied before processing the metal plate. This PCM is cut to size and worked or processed by welding or bonding to produce an ultimate assembled product.
However, since the coated metal plate is welded, problems are presented in that toxic gases may be produced due to burning of the coating at the time of welding, or only an insufficient bonding strength may be produced. The bonding by the adhesive also suffers from the drawback that the operation of applying the coating is highly complex, while only an insufficient bonding strength may be produced due to the presence of the coating. When the paint is applied after the working or assemblying for obviating these inconveniences, the metal sheets may be rusted while being left before processing. When the paint is applied after working or processing, the coating efficiency may be lowered significantly due to the complex shape of the products.
The present inventors have conducted eager researches towards overcoming these problems and arrived at a composition having not only the function of a protective material for affording an aesthetic appearance and durability such as the corrosion resistance, waterproof and resistance to chemicals, to a base material coated with the composition, but also the function of bonding two base materials coated with the composition to each other when these base materials are applied to each other under heating and pressure application. This finding has led to fulfillment of the present invention.